Advanced Materials Research Vols. 97-101

Abstract: In this paper, four axisymmetrical finite element models have been established to study effect of thinckness on residual stress fields of cold expansion hole, experiments were carried out to measure the residual stress of cold expansion hole and verify simulation results. The experiment results also show that cold expansion processing can decrease surface roughness of holes and improve surface quality. The FEM results show, at the top(bottom) surface, the volue of the radial residual stress varies with the plate’s thickness, and the regularities of distribution of the radial residual stress are identical. The volue and the regularities of distribution of the circumferential residual stress vary with the plate’s thickness. At the mid-thickness surface, the volue and the regularities of distribution of radial residual stress vary with the plate’s thickness. The volue of the circumferential residual stress varies with the plate’s thickness, and the regularities of distribution of the radial residual stress are identical.

Abstract: The cross-linked UHMWPE mixed with Vitamin E (VE) was prepared by hot press and then irradiated with gamma radial of 100 kGy does. The scratch hardness, micro-hardness and cross-linking density of cross-linked UHMWPE was measured. The tribilogical behavior also was examined. The experimental results indicated that the scratch hardness and micro-hardness of irradiation virgin and NC/UHMWPE are higher than that of virgin UHMWPE. Mixing VE decreased the cross-linking density of irradiated UHMWPE. Friction coefficients of virgin and cross-linked UHMWPE were seldom affected by irradiation and mixing VE. It was ranged from 0.35 to 0.37. Wear rate of virgin and cross-linked UHMWPE were strongly influenced by irradiation and mixing VE. Wear rate had an inverse proportional to the scratch hardness. The cross-linking and mixing VE in UHMWPE change the severity of adhesive wear of UHMWPE. For virgin UHMWPE, irradiated virgin UHMWPE and 0.1wt%VE/UHMWPE, the severity of adhesive wear was gradually decreased. Besides adhesion, poluging was the wear mechanism of irradiated 0.3wt%VE/UHMWPE.

Abstract: The effect of severe plastic deformation method on the dissolution of θ’phase in Al-Cu binary alloy was investigated by employing equal channel angular pressing(ECAP) and multi-axial compression(MAC). The results suggested that a more rapid dissolution of θ’ phase occurred in the MAC processed sample comparing with the ECAP processed sample, which was attributed to the stress state difference between ECAP and MAC processed samples .

Abstract: Rheological behaviors of Sn melt were systematically studied using a comprehensive measurement instrument designed in our lab. Structure of the Sn melt was analyzed by a liquid XRD technology. The result indicates that in the vicinity of 400°C, 800°C and 1200°C, the melt is a non-Newtonian fluid, while it is a Newtonian fluid within the temperature ranges of 400—800°C, 800—1200°C and over 1200°C. It is evidenced that the rheological property of the Sn melt is correlated to the changes in the melt structure. When the temperature is raised, the correlation radius rc, the coordination number Ns decreases, while in the vicinity of 400°C and 800°C, the correlation radius rc and the coordination number Ns of the Sn melt all show discontinuous changes.

Abstract: The analysis and the test about the relationship between the wear and the thermoelectric potential of YW1 cemented carbide inserts have been finished in this paper. The influence rules and the influence extent of thermoelectric potential to the wear have been emphasized. Then the new method of forecasting the life of cemented carbide has been also discussed.

Abstract: The existence of viscosity effect at the interface of double dissimilar materials has an important impact to the distribution of interface crack-tip field and the properties variety of the interface itself. The singular is considered in crack-tip, and the elastic-viscoplastic governing equations of double dissimilar materials at quasi-static propagating interface crack-tip field are established. The displacement potential function and boundary condition of interface crack-tip are introduced, and the numerical analysis of rigid-elastic viscoplastic interface for mode II are worked out. The stress-strain fields are obtained at the crack-tip and the variations of solutions are discussed according to each parameter. The numerical results show that the viscosity effect is a main factor of interface propagating crack-tip field, and the interface crack-tip is a viscoplastic field that is governed by viscosity coefficient、Mach number and singular factor.

Abstract: The time-correlated leakage characteristic of nonmetallic gaskets was analyzed. Considering the effect of the gasket material deterioration on the sealing performance, a time-correlated leakage predication model of nonmetallic gasket sealing connections based on the porous medium theory was proposed. Some tests were performed on compressed non-asbestos fiber gaskets, the leakage behavior was investigated and the coefficients in the leakage model were obtained by regression analysis of experimental data. The predicted leakage rates according to the model were compared with the data reported in some literatures, and the prediction accuracy was also validated. The presented time-correlated leakage model provides an effective way to predict the leakage rate and evaluating the life of gasket sealing connections.

Abstract: A ferrocenyl Schiff base monomer was synthesized through the condensation of ferrocenecarboxaldehyde and phenylenediamine under neutral conditions, and then been used to produce copolymer materials with terephthaloyl chloride monomer by the Friedel-Crafts method. The model compound and copolymer of a novel poly(ferrocene-Schiff base) and their charge transfer complex with iodine was successful obtained, their structures been characterized by 1H-NMR spectra, infrared spectra, and ultraviolet spectra. In addition, the effects of iodine doping degree on its structure was studied, the electrical measurement results showed its conductivity can be increased several orders of magnitude after doping with iodine, the maximum conductivity at room temperature is 3.17×10-4 S•cm-1.

Abstract: This paper presents a numerical method that can predict the Young’s modulus of ceramic with reasonable accuracy. By introducing periodic conditions, the distribution of pores in the matrix phase is simulated. The lattice model is then employed for the analysis of stress in the pore structure and for the determination of the maximum element length. Finally, the validity of the proposed numerical method is preliminarily verified with the experimental results obtained from the literature.

Abstract: The aluminized layer and the La-aluminized layer on 20 carbons steel were prepared by hot dip aluminizing method, and the microstructure and composition of the layer were investigated through scanning electronic microscopy (SEM), transmission electron microscope (TEM), X-ray diffractometer (XRD) and energy dispersive spectroscopy (EDS). The results showed that the amorphous phase was found in the surface layer of the hot dip aluminized steel. In order to study the phenomenon, the Al-Fe alloy liquids used in hot dip aluminizing were quickly solidified and slowly solidified respectively. The results showed that the amorphous phase was found in all Al-Fe alloy samples under the condition of the quick solidification. While the amorphous phase was only found in Al-Fe alloy sample with La under the condition of the slow solidification. Moreover, the pure amorphous alloy exists in the parts region of the sample, and the weight percentages of Al and Fe in pure amorphous alloy was 23: 2, and the amorphous alloy composition also contains a small quantity La. The formation mechanisms of the amorphous phase and behavior of La in the hot dip aluminized layer were also discussed.